Concerned Thai authorities have imposed stricter checks on animal feeds imported from Vietnam after shipments of squid viscera meal were found contaminated with melamine.

The animal feed, weighing a total of 60 tonnes, had been imported by two Thai companies, the Bangkok Post reported.

Apai Suttisunk, head of the Department of Livestock Development, was quoted as saying that the feed had traces of cyanuric acid, a component of melamine, which is a chemical banned for animal feeds.

"We have put the manufacturer on a blacklist," Apai said, adding that they had asked the Vietnamese government to ban the manufacturer from exporting products to Thailand. The manufacturing firm was not named in the news report.